Incobposated



'45. wrm Y. it.

Hannie Bovine, or'nnw Yoran,

SEEN T0 'WESTEET ELECTRIC COMPANY,

INCDRPORATED, OF NEW YORK, N. V., COtPEtTEGH' F NRV/T YRK.

ELECTBCAL PZSTECTVS DEVCE.

To all lw/tom may concern.'

Be it known that l, lclnnnrn Bovins, a citizen of the United States, residing at lleiv York, in the county of New York and State of New York, have invented certain nen7 and useful Improvements in Electrical lircaecv tive Devices, of which the following is a full, clear, concise, and exact description.

rlhis invention relates to devices for protecting electrical circuits 'from abnormal voltages, lightning and similar discharges and more particularly to protective devices o1" the' type adapted to provide a ground connection'for a circuit when its potential is raised to an abnormal value.

The type of protector commonly used for protection of circuits of low normal operating voltage consists' essentially of two electrodes spaced apart a t'eW thousandths of an inch, one of these electrodes being connected to ground and the other connected to one Wire of the line to be protected. ln order that a protector of this type may afford the -required degree of protection and at the same time not require an excessive amount of maintenance, it is not only necessary that the electrodes be spaced apart the proper distance, but also that the design be such that this separation is not altered by service conditions. ln protectors so designed that the conducting blocks or electrodes are separated by means. of a sheet of insulating material, more or less trouble is experienced due to the formation of a bridge or' conducting material over the edge of the separator as the result of repeated discharges. @n the other hand, in the case of protectors not employing insulating separators but depending upon the conducting electrodes being properly spaced in, an insulating block, diiiculty has been experienced in' obtaining a cementing means which does not cold-flow at normal operating temperatures.

lt is the object of the present invention to provide a protector in Which the electrodes are secured in place by means of a material which is non-hygroscopic, non-iniiarnmable and which is not subject to cold flow under normal temperatures.

A further requirement of this materia-l is that it shallv soften and become plastic in case the blocks attain a temperature involvin a fire hazard. To accomplish this resulgt, the invention provides a protector in which electrodes are secured piece by Specification of Letters fatent.

Application filed August 16, 191?, Serial No. i843;

.Patented Dec. 9, i919.

Renewed lune il, 1919. Serie). lo. 303,475.

means of a loir-melting point glass, this mau tcrial being free from the defects inherent i rions cements used heretofore.

accompanying drawing, Figure 3. a side elevation of a protector embodying e features conten'iplated by this invention; d Fig. 2 is a cross-sectional vien7 aloner the line 2 2 of liig. l.

.me protector shown in the drawing comprises a block 8A of porcelain or similar insulating material in which are mounted the opposing electrodes il, 5 of conducting material, preferably carbon. These electrodes are accurately spaced a definite distance apart by means of a. gage inserted in the opening 6 and after the blocks have been heated, are secured in placevlby means of threads or iillets 7 of low-melting point glass'. For 'this purpose lead-berate glass consistingof approximately 85% lead-oxid and 15% boric acid has been found to be particularly suitable.

This material, which is lnon-inflammable and non-hygroscopic, becomes plastic at approximately 360 C. and is not subject to cold dow at normal operating temperatures. As the method oie mounting these electrodes is Well understood in the art, being` illus trated, for example, in lJVilliams Patent 588,206, August 17, 1897, it is thought to be unnecessary to illustrate the method in the present case.

ln service the electrodes ei and 5 engage respectively a ground plate and a line spring, the latter being under considerable tension. ln the event of a high resistance cross with a power or lighting circuit, the arc formed between the electrodes, if allowed to continue, would generate suiilcient heat to draw the temper from the spring and cause a dangerous fire hazard. However, with the proposed construction the glass becomes plastic before this dangerous temperature is reached and the tension of the protector spring forces the electrodes together, thereby providing a low resistance path to ground and eliminating all danger from arc-J mg.

l/lhat is claimed is:

l. ln a protective device, conducting blocks held adjacent each other but separate from one another, supporting means for one or' said blocks, said block being held in osition in said supporting means byv a. owf melting point glass,

2, In a protective device. a pair of enuduetmg hioeks held adjacent to butseparate 'from one another. one of said blocks compriamg an eleetrode of eonduetmg material secured 'to a member of non-emuhwt'ing material by means` of a low-melting point glass.

3. In a protective device.y a pair of conducting blocks held adjaeent to but separate from one another` one et' said bloei@l com prisingan eleetrde of emulueting material secured to a member of non-'condiieting material by means (rf lead-bolate glass eonsisting of approximateiy 85?? iead-oxid and 15%' boric acid.

4. In a protective device, a pair of eondueting blueks, held adjacent tu but separate from each other. (me of said bioeks eom prisiug a earbon electrode secured to a poreeiaiu member by means mi a low-melting point glass.

In witness hei-enf. I hereunto subscribe my name thia 15th day 01' August, A. D. 

